Numerical Modeling of Reverse Fault Rupture and Its Impact on Mountain Tunnels

Abstract

ABSTRACT Active faults pose significant threats to the structural integrity of mountain tunnels in seismic active zones. Post-earthquake reconnaissance revealed that numerous tunnels were damaged during past earthquakes, specifically those crossing active fault zones. In this study, the structural response and damage mechanism of a water conveyance tunnel subjected to reverse faulting was investigated. A three-dimensional finite element model incorporating the cohesive interface elements was developed to simulate the nonlinear process of the reverse fault rupture. The ground deformation and tunnel damage characteristics predicted by the numerical analysis were in good agreement with the field observations and experimental results, which proved the feasibility of the proposed simulation scheme. Moreover, a parametric study was conducted to estimate the effects of dip angle, surrounding rock property, tunnel rigidity, and friction coefficient between linings on tunnel performance. The results showed that the damage zone with softer rock masses of grade IV to V, based on the Chinese Guidelines for Design of Highway Tunnel, generally led to moderate structural damage to the tunnel. The tunnel’s performance in the damage zone can be further enhanced by increasing tunnel rigidity and smoothness of the external surface of the secondary lining.